FLOOR STRUCTURE INCLUDING PREFABRICATED FLOOR UNITS

Abstract: The invention relates to a floor structure (1) with prefabricated floor units (2, 3) of reinforced concrete, and a process for manufacture of such floor units. Each floor unit (2, 3) is comprised of a base plate (4) and T-beams (6) arranged on the base plate essentially parallel to each other. The beams are securely anchored to the base plate (4) by means extending from each beam and disposed on a reinforcing ladder (14) cast in the web of the beam (6), whereby open channels (12, 13), into which electrical and telecommunication wiring and plumbing can be mounted, are formed between two adjacent beams (6). The floor structure (1), after drying out of the units (2, 3) at the factory, can be mounted in the building frame at any selected time prior to joint casting, casting together or under-casting of the walls.

Description: Floor structure including prefabricated floor units The invention relates to floor structures comprising prefab- • » ricated floor units of reinforced concrete for mounting in a multistorey structure frame, preferably also constructed of prefabricated outer and inner wall units, of the type dis- 5 closed in the preamble of claim 1, and a process for manu¬ facturing units included in the floor structure, in accord¬ ance with claim 6. Conventionally, such concrete floor structures are usually 0 made by on site casting with a subsequent long drying time. This requires moulds shored up by posts and support struc¬ tures involving interruption of the work of raising the frame even when casting intermediate floor structures, and it can not be resumed before the stipulated period of time has 5 passed after casting. There is, however, the risk that the drying time will be too short and moisture enclosed in the floor structure will be sealed in by coating with watertight floor materials. Further treatment is required in most cases by evening out or height adjustment with spackle for example, 0 in order to achieve the required dimensions and surface finish on the top of the floor structure. Prefabricated floor structure units which are homogeneous or pretensioned are also known, but these have, however, a rela- 5 tively high weight and have in certain cases weight-reducing grooves enclosed within each unit, thus making impossible hidden subsequent insulation of e.g. distribution boxes for electrical, telecommunications or plumbing connections. 0 SE 310 249 describes a floor unit for assembly, which is pre¬ fabricated in a factory and is constructed of a concrete slab with parallel beams in the form of T-beams. The beams are ' anchored in the concrete slab by casting together, and the ends of the reinforcements placed in the beams are cast into 5 the concrete slab. Open channels are formed between the beams. One disadvantage of this floor structure unit is that the T-beams are shorter than the concrete slab and thus do not reach up to the wall structures, and this will result in severe downward deflection and possibly buckling of the bottom slab next to the wall structures. Furthermore, when making joints to the wall, there is no rigidifying reinforce¬ ment at the top of the floor structure extending over each support, and this results in increased downward deflection causing discontinuous floor structures over the wall sup- ports. The purpose of the invention is therefore to provide a dry floor structure of the type described by way of introduction, which is supported by prefabricated floor units, which have a predetermined stiffness with very little sag, low weight and having open channels in the joint portions over supports and towards the topside, said units being installable in a build¬ ing frame at any selected time during construction without hindering the frame assembly. It is possible to subsequently mount in the channels junction boxes for the building and, except for the joint casting, no further working, evening or adjustment is required of the installed floor structure at the site. Joint casting and top and bottom casting of the walls can be done after installation of the floor structure units several storeys up, and this has great advantages during the winter months, since the construction can quickly be roofed over, thus facilitating supply and retention of heat. This is achieved according to the invention by the floor structure with the characterizing features of claim 1 and the process of manufacturing prefabricated floor units included in the floor structure in accordance with the characterizing features of claim 7. Advantageous further developments and improvements of the invention according to claims 1 and 7 are made possible by the steps disclosed in the dependent claims. Each floor unit is composed of a base plate and joists secu¬ rely anchored to the base plate and extending from edge to edge of the base plate and being essentially parallel to each other, and being anchored to the base plate by means extend¬ ing from the portion of the joist facing away from the flange, thus forming open channels between two adjacent joists, said unit being installable in the building frame at any selected time. The units are manufactured by mould casting a base plate, with high demands as regards dimensional accuracy and surface finish, in a conventional manner with prefabricated joists fixed in the mould. The joists are prefabricated in a special mould, also with high requirements as regards dimensional accuracy and surface finish, and portions of the reinforce¬ ment in each joist are allowed to protrude from one of the edges of the joist, and said portions are thus anchored in the concrete of the base plate when the base plate is cast. The invention will be described in more detail below with reference to an embodiment shown in the accompanying schema- tic drawing only as an example. Figure 1 shows, in section, a floor unit made of a base plate provided with joists, Figure 2 shows, as seen from above, a joist in the form of a T-beam, Figure 3 shows, in section, the joist according to Fig 2, Figure 4 is a perspective view of a floor structure portion with sound-insulating flooring, Figure 5 shows, in section, the connection between the walls and the floor structure in a building frame, Figure 6 shows, from above, the casting together of floor structures over supports, Figure 7 is a cross-section of the casting together according to Fig 6, and Figure 8 illustrates a process for manufacturing the joists used in the floor structure units. A floor structure 1 has at least one supporting floor struc¬ ture unit 2,3, comprising a base plate 4 with joists 6, said units preferably being made of reinforced concrete. The base plate 4 is dimensioned to applicable fire and sound specifi¬ cations, and this in general requires a thickness of 80 mm. Each joist is suitably in the form of a T-beam 6, having a web 8 and a flange 10 across one of the edges of the web, forming a 90 angle with the web, and extending approximately equadistant to either side of the web. T-beams are joined, preferably cast together, with the base plate with prede¬ termined spacing, extend from edge to edge of the base plate, and are parallel to each other and with the longitudinal lateral edges of the plate, thus forming open channels 12 between two adjacent beams 6. As will be described below, transverse channels 13 are formed between the outer ends of connecting beams when joined over supports. A preferred spacing between the beams is 0.8 m and a suitable length of a unit is 4-6 m, suitable width is 2.4 m and a preferred dis¬ tance between the underside of the base plate 4 and the top of the beam flange 10 is 260 mm. Each unit 2,3 is made in accordance with building regulation tolerances as regards height and surface finish, and no further evening or smooth¬ ing, e.g. with filler, is required on site. Each T-beam 6 has a reinforcing ladder 14 cast into its web 8, and consisting of diagonally transverse reinforcing rods 16,17, which interconnect parallel longitudinal reinforcing rods 18,19, which are so arranged that a reinforcing rod 18 is located close to the central portion of the junction between the beam web 8 and the beam flange 10, and extends along the length of the beam. At either side of the reinfor- cing rod 18, ends of two diagonal rods 16,17 are welded, so that the rods in the cross-sectional plane of the beam form a small positive angle of 2-5 with each other. Close to each of the free ends of the diagonal rods there is welded an individual longitudinal reinforcing rod 19, so that both of the rods 19 are parallel to the rod 18. The width of the ladder 14, i.e. the distance between the two rods 19 and the single rod 18, is preferably 190-210 mm and its length de¬ pends on the intended length of the T-beam and therefore varies with the length of the floor structure unit which is to be manufactured, within the above stated interval of 4-6 . In the longitudinal direction of the reinforcing ladder, a number of pairs of diagonal reinforcing rods 16,17, adapted to the length of the T-beam, are welded in a corre¬ sponding manner between the rods 19 and the rod 18, said pairs being parallel to each other in the longitudinal plane of the beam and forming an acute angle of 50-70° with the adjacent pair of diagonal rods. Thus, the diagonal rods form a zig-zag ladder pattern. The reinforcing ladder 14 projects with the free ends of the diagonal rods 16,17 and the paral¬ lel rods 18, from the concrete in the web of the T-beam, approximately 30-60 mm in order to make possible reliable casting together with the base plate. In the two opposite lateral edges of the beam flange 10, notches 20 are made with regular spacing, essentially corre¬ sponding to the length of the notches, thus producing projec¬ tions 22. The lateral edges of the beam flange are thus provided with a toothed profile 23, which is intended to increase the force-transmitting capacity of the floor struc¬ ture units in connection with casting together with supports. In this case the toothed profile 23 is used to achieve a positive grip in the joint. The connection between the walls and the floor structure and the connection of floor struc¬ tures to each other will be described in more detail below. The floor structure 1 is suitably provided with a pair of sound-insulation strips 24 disposed on the outside of each beam flange 10, on which non-attached flooring 26 rests, thus providing good sound-insulation properties. Owing to the fact that the T-beams 6 are produced in a smooth mould pallet, which will be described in more detail below with reference to Fig 8, the outside of each flange 10 has "a final finish" and requires no subsequent treatment prior to application of the strips 24. The flooring 26 is usually particle board, but for higher safety requirements and for clinker flooring, cement-bonded tiles are more suitable. The floor structure units 2,3 can be installed in a building frame of a multi-dwelling structure, which, as can be seen in Fig 5, comprises an outer wall 28 and an inner wall 30. The outer wall is composed of prefabricated units, e.g. of the type disclosed in Swedish Patent Application 9203033-7, and both the outer wall 28 and the inner wall 30 each have a supporting surface 32 and 34, respectively, for individual opposite longitudinal side edges 36 and 38, respectively, of the unit 2. Next to the edge 36 and 38 of each unit, anchor- ing loops 40 are embedded, which can be joined to reinforcing rods 42 extending both from an upper and a lower wall unit and which at the same time can be used as lifting eyes. Each floor structure unit 2,3 can be fixed by means of reinforcing rods 42 in the building frame by concrete 44 being cast up to the underside of the beam flange 10 of each T-beam, in the space between the T-beam and the adjacent supporting surface 32 or 34. When the concrete in the cast is thoroughly dry, it is possible to install the necessary cables or pipes on the top thereof or in one of the channels 12, which is then enclosed by the mounting of the flooring 26. As can be seen in Figs 6 and 7, the floor structure units 2,3 can be cast together over a support, e.g. a wall, by joining two floor structure units along the edges 46,48 of their short sides, said edges facing each other and resting on supporting ends 50,52 of the wall. The channels 13 made between the edges 46,48 and the supporting surfaces 50,52, can, as can the channels 12, be used for hidden lines. According to Fig 5, reinforcing rods 54 extend from both an upper 56 and a lower 58 wall unit in the joint portion, for casting together with the floor structure units 2,3. Further¬ more, a reinforcement is arranged at the upper edge of the floor structure by extending reinforcing rods 60 over the wall unit 58, parallel to and level with the toothed profile 23 of the facing units 2,3. Said reinforcing rods 60 are intended, after casting, to hold the floor structure units 2,3 together over the wall unit 58. In order to facilitate the joint casting, barriers 62 are disposed in facing cavi¬ ties 20 in the respective toothed profiles 23. When the concrete in the joint iε thoroughly dry, the floor structure is ready to be covered by a suitable flooring 26. The prefabricated floor structure units 2,3 are manufactured by fixing the prefabricated T-beams 6 in a mould, which is prepared with reinforcement for the base plate, at the right height and with the correct spacing, preferably 0.8 m, where¬ after casting is done to the correct thickness, which in this case is approximately 80 mm. The T-beams are fixed at such exact tolerances that no additional height adjustment is necessary after assembly in a building frame. Each T-beam has a total length which extends over the entire mould, so that the beam ends are aligned with the supporting edges of the base plate in the finished floor structure unit. The T-beams are manufactured in a smooth mould pallet 64, in which square pipes constitute the mould bodies 66, with barriers 68 against a bottom 70 of the pallet, thus providing the desired T-shape (Fig 8) . The pallet bottom 70 is suitably variably deflectable downwards so that an upward curvature can be achieved in the middle portion of the T-beam. The reinforce¬ ment in each beam 6 consists of the prefabricated reinforcing ladder 14, which is placed in the mould with the reinforcing rod 18 at a suitable height h above the pallet bottom 70, where h assumes values in the interval 18-25 mm and is orien- ted as was previously described so that the reinforcing rods 19 and 30-60 mm of the ends of the diagonal rods 16,17, after casting, protrude from the concrete for subsequent casting in the bottom plate. Each mould body 66 is fixed with itε lift¬ ing chain 72 in a lifting yoke 74 which, when the mould bodies 66 are applied with the barriers 68 reεting against the bottom 70 of the pallet, is lowered over the mould. Concrete is poured in to a suitable height in the mould. By varying the amount of concrete, it is easy to achieve the desired web height, and when the concrete haε become cured, the mould is "plundered" as follows. Both ends of the lifting yoke 74 have pressure pistons 76 with piston rods 78 directed against each other, and having individual pressure plates 80. By operating the pistons towards each other, the pressure plates 80 are pressed against the mould bodies 66 adjacent the outer edges of the mould 64. The opposite sides of the mould bodies are pressed in turn against the adjacent T-beam, which is pressed against the adjacent mould body and so on, whereby all of the mould bodies 66 and the T-beams 6 are clamped in the lifting yoke 74 and can be lifted out of the mould at the same time. The beams can then be placed as desired, e.g. on a table, ready for turning and picking up. The pressure pistons 76 are then operated in the opposite directions, thus releasing the pressure plates 80 from the mould bodies 66 which are then lifted up via the lifting chains 72, are oiled and placed again in the mould pallet. The moulded T-beams are thus provided with a "final finish" on the outside of the beam flange 10 and are now ready for turning, fixing and casting into the base plate. The floor structure unit provides both support for above lying wall units and permits subsequent installation of electrics and plumbing and permits continued work several storeys up, which provides for uninterrupted asεembly. After installation of electrical wiring and plumbing, the under- casting is done and the wall unit is cemented both below and above the floor level, at the same time as there is continu¬ ous cementing of the floor structure units on either side of the supporting surface at the top, which reduces deflections and provides a continuous flooring structure. The relatively small amounts of water which are added to the joint casting dry quickly and do not extend the drying time appreciably. The unit permits it to be open under the walls when the T- beamε are installed, which in turn permits laying of both ventilation ducts and waste water piping under the wall. It is thus possible to do subsequent installation prior to casting together. In connection with the undercasting, the walls are cemented both upwards and downwards at the same time aε the floor structure unit is cemented, and this pro- vides continuouε floor structures and small deflections. Finally, it is pointed out that the present invention should not be considered to be limited to the particular embodiment described above. Rather, the invention comprises all those embodiments and equivalent solutions which fall within the scope of the following patent claims. Thus, the reinforcing ladder cast into each T-beam does not need to be a double ladder as described above but can be a ladder with single diagonals and a longitudinal rod along each side.

Claims: Claims 1. Floor structure (1) comprising prefabricated floor units (2,3) of reinforced concrete for conεtruction of a multi¬ storey building frame comprising prefabricated outer wall (28) and inner wall units (30,56,58), said floor units (2,3) each having a base plate (4) and essentially parallel joists (6) securely anchored to the base plate (4) , thus making open channels (12,13) between two adjacent joists (6) , each of which is in the form of a T-beam (6) , which has a web (8) and a flange (10) , oriented essentially at right angles thereto, c h a r a c t e r i z e d in that the T-beams (6) at least bridge the total distance between two supporting edges of each base plate (4) , and that the units, after drying in a factory, can be mounted, at a selected time prior to joint casting, casting together, or over and under casting of walls, in the frame of the building at a plurality of storeys resting on each other. 2. Floor structure according to Claim 1, c h a r a c t e r ¬ i z e d in that open channels (13) are made between opposite edges (46,48) of adjacent floor units (2,3) and supporting wall units (58) , and that the end portions of the beams (6) extending into the edges also constitute supporting surfaces for the wall units (56) thereabove. 3. Floor structure according to Claim 1 or 2, c h a r a c ¬ t e r i z e d in that the fixing means (16, 17;19) joining the beamε (6) and the baεe plate (4) are disposed on at least one reinforcing ladder (14) prefabricated of reinforcing rods, said ladder constituting at least two thirds of the cross section and being cast in the web of the beam (6) . 4. Floor structure according to one of the preceding claims, c h a r a c t e r i z e d in that distribution boxes for electrical wiring, telecommunications and plumbing can be mounted in the channels (12,13) prior to the required joint casting of the units (2,3) and casting together with outer and inner wall units (28,30) . 5. Floor structure according to one of Claims 2 - 4, c h a r a c t e r i z e d in that a floating floor (26) rests on sound-insulating strips (24) , which are in turn laid on the topsides of the T-beams (6) . 5 6. Process for manufacturing floor structures according to * one of Claims 1 - 5, involving prefabrication in a special mould (64,66,68) of the T-beams (6), portions (16,17;19) of the reinforcement (14) of each beam being allowed to project 0 from one of the edges of the beam, that the beams (6) after curing are fixed in a mould (64) , which is prepared with reinforcements for the base plate (4), c h a r a c t e r ¬ i z e d in that the beams (6) at least extend between the edges of the mould (64) , that the base plate is cast thereon 5 in the mould (64) with high demands as regards both dimen¬ sional accuracy and surface finish, and that the beams are thereby anchored via the respective reinforcing parts (16, 17;19) to the base plate along its entire width. 0 7. Process according to Claim 6, c h a r a c t e r i z e d in that the beams are manufactured in a smooth mould pallet (64) , in which mould bodies (66) parallel to each other are immersed to predetermined positions, that each body (66) haε a barrier (68) against the bottom of the pallet to permit 5 casting of the beams (6) , with a crosε-sectional profile depending on the shape and relative positions of the bodies (66) , and that the outside of each beam flange (10) is made thereby with a high surface finish against the bottom of the pallet (64) . 0 8. Process according to Claim 7, c h a r a c t e r i z e d in that prefabricated reinforcing ladders (14) are lowered and centered between two adjacent bodies (66) , the length of said ladders essentially agreeing with the length of the 35 bodies, that each reinforcing ladder (14) is placed with one longitudinal side at a level (h) above the bottom (70) of the pallet, corresponding to at least one third of the distance between the respective body (66) and the base (70) , and that the concrete (44) is thereafter poured to a level lower than the top of each body (66) and that a portion comprising the opposite longitudinal side (19) of the ladder (14) iε left free of concrete in an interval corresponding to one eighth to one third of the width of the ladder (14) . 9. Process according to one of Claims 6 - 8, c h a r a c ¬ t e r i z e d in that, when the concrete has cured, a lift¬ ing yoke (74) is lowered over the pallet, that pressure pis¬ tons (76) joined to pressure plates (80) are then operated towards each other, whereby the mould bodies (66) and the cast beams (6) are pressed against each other and are held in the lifting yoke, by means of which the bodies (66) and the beams (6) are lifted together out of the mould for selected placement on a table for example, whereafter the pressure pistons (76) are operated in the opposite directions, thereby releasing the bodies (66) from the beams (6) , that the mould bodies (66) are lifted once again, hanging in the lifting yoke, and are again prepared for placement in the mould pallet (64) . 10. Process for manufacturing floor structures according to one of the preceding claims, c h a r a c t e r i z e d in that two floor units (2,3) are placed with the edges (46,48) of the short sideε resting on a wall support (50,52,58), that upper wall units (56) are placed resting on the end portions of the T-beams (6) extending at the edges (46,48), that rein¬ forcing rods (60) are placed extending over the wall support (58) at the upper edge of the units (2,3), that required wiring or plumbing is carried out in the channels (12,13), and that casting together is then carried out by means of embedding the reinforcing rods (54,60) and the toothed pro¬ files (23) , thus providing a continuous floor structure (1) over the wall support (58) after curing.

Inventors: JUGAS HENRY, JUGAS, HENRY
Applicants: DALA CEMENTVARUFABRIK AB, JUGAS HENRY, AB DALA CEMENTVARUFABRIK, JUGAS, HENRY
Application year: 1994
Main classification: E04B5
IPC codes: B28B13, E04B5